It is known to use a liquid mixture containing a less dense liquid component and a more dense liquid component, for the purpose of removal of water containing films and substances carried by the water film being substantially immiscible in the aforesaid cleaning fluid. Illustrative of this type of prior art are: U.S. Pat. No. 3,125,106 to Brucken et al., U.S. Pat. No. 3,559,297 to Figiel, U.S. Pat. No. 3,589,023 to Figiel, U.S. Pat. No. 3,710,450 to Figiel, U.S. Pat. No. 3,733,710 to Kearney et al., and U.S. Pat. No. 4,136,217 to Henley. The Kearney et al. patent shows separation of a liquid mixture using a conventional water separator to separate water from the more dense liquid. The Henley patent shows an overflow pipe 26 for overflowing a top portion of a liquid mixture that has an oil emulsion as the top portion and wash water as the bottom portion. The liquid overflow is allowed to reach a quiescent condition so that there is formed an oil layer and a water layer. The oil layer is removed by a conventional rotating belt oil skimmer 30.
The Figiel patents show a process in which the liquid mixture thereof is allowed to overflow from one tank into a second tank. The second tank has an overflow pipe for removing the less dense liquid, and a drainpipe for removing the more dense liquid. Drainpipe 7 in Figiel, U.S. Pat. No. 3,710,450 runs upwardly and parallel to wall 8 before turning to empty into reservoir 9. The height of drainpipe 7 determines the level of solvent in water separating pump 4. Overflow pipe 6 is connected to the water separating pump at a point slightly above the level of drainpipe 7.
This prior art and the other prior art of which we are aware fails to provide a practical apparatus or process or a cleansing system which lends itself to an operation in which non absorbent articles may be cleansed while the cleansing fluid containing the hydrophilic liquid phase, that has been removed from the non absorbent articles, is continuously processed to separate therefrom this hydrophilic phase and any contaminants removed from the surface of the articles. The cleansing fluid which is characterized as the more dense component is itself comprised of a less dense liquid, e.g., an aliphatic alcohol, and a more dense liquid e.g., trichlorotrifluoroethane. This less dense liquid present in the cleansing liquid is miscible in the more dense liquid in amounts of from 0.1% to about 10%. However, the hydrophilic film cleansed from the surface of the non absorbent articles is not miscible with cleansing fluid in amounts greater than about 0.1% by weight. This property of the cleansing fluid provides surface wetting of non absorbent articles and facilitates separation of the hydrophilic film from the surfaces of the non absorbent articles to be cleaned and thereafter separation from the more dense cleansing fluid of this hydrophilic phase. Rapid removal of this hydrophilic liquid and contained contaminants are important since this minimizes dissolution of same in the dense liquid and retains the efficiency of the cleansing system.